The present invention relates very generally to a motor construction for use in an electrical appliance which operates at different motor speeds.
Conventional manufacturing of electrical appliance motors is both time consuming and relatively expensive. For example, according to known methods of making a stator of a multiple pole motor there are difficulties in insulating the flux wires from the metallic body of the stator. Typically, the entire stator must be coated or treated with material such as fish paper to prevent the windings of the coil from contacting the stator body. The stator must then be capable of passing what is known in the industry as a High Pot Test. However, even after the above steps are taken, there is no guarantee that there may still not be areas of electrical conductivity between the stator and the flux wires which produce electrical shorting of the motor which will show up in the High Pot Test.
In addition to not necessarily being completely efficient, the above steps are also very labour intensive adding significantly to the cost of the motor.
Again, in a traditional electrical appliance motor, it is very difficult to maintain lubrication of the rotor in the motor. Traditional bearings may not be effective and may result in overheating of the motor.
A further difficulty encountered in the manufacturing of a standard electrical appliance motor relates to the actual wiring of the motor. Traditionally electrical leads or terminals are connected directly to the ends of the flux wires internally of the motor housing. The connections must be made either by crimping or soldering and insulating the terminal leads to the ends of the flux wires. Again, this is very labour intensive and substantially slows down the assembly time for the overall motor. In addition, it necessitates the use of relatively costly leads and additionally necessitates the use of expensive multipole switches that must then be mounted to a separate location on the appliance.
As a further drawback, electrical appliances such as electrically operated fans traditionally use mostly metal components which are all manufactured separately from one another and which then are typically secured by mechanical fasteners such as screws further adding to the cost of the appliance from both a material and a labour standpoint.
The present invention provides a motor construction for an electrical appliance which essentially overcomes all of the drawbacks listed above with respect to traditional electrical appliance motor constructions.
More particularly, according to an aspect of the present invention, an electrical appliance, which operates at multiple speeds and which comprises a motor construction includes a stator and a rotor which rotates within the stator. The stator comprises a plurality of magnetic flux inducing wires coiled on poles within the stator. The stator and rotor are contained within a motor housing and the appliance further includes a switch housing mounted directly to the motor housing. The flux inducing wires rather than being connected to terminal leads within the motor housing have wires ends which extend out of the motor housing and directly into the switch housing. The switch housing includes receptors which receive the ends of the flux inducing wires and which also receive electrical contact members. These contact members secure and electrically connect with the ends of the flux inducing wires within the receptors of the switch housing.
According to another aspect of the invention, the stator of the motor construction includes a resin bobbin which is accurately injection molded to the main metallic body of the stator. This bobbin receives and isolate the magnetic flux wires from the metal body of the stator eliminating the separate dipping processes and the like which have been used in the past on a somewhat ineffective basis to prevent shorting between the windings and the stator.
The injection molding of the bobbin also eliminates the old requirement of riveting the entire stator parts together. This is not necessary in accordance with the present invention where the stator and bobbin are secured by the molding process.
According to still a further aspect of the present invention, the motor construction includes an extremely efficient lubricating bearing assembly adding longevity to rotor life.
According to yet a further preferred embodiment of the present invention a substantial part of the overall appliance including the bearing housing, the motor housing and the switch housing and switch body are all made from plastic in a single injection molding operation. This plastic is one with suitable electrical and mechanical properties to comply with OSHA standards and to pass UL and CSA testing. Furthermore, most of these components are ready to assemble with one another by automatic interlock fittings eliminating the requirement for separate mechanical fasteners throughout most of the overall appliance construction.